RU2268246C1 - Method for briquette production from powdered materials - Google Patents

Abstract

FIELD: metallurgy, foundry, building industry, in particular method for material briquetting.

SUBSTANCE: method for briquette production from powdered materials, preferably from metallurgy waste includes material mixing with cement, processing additive and water. Further mixture is fed into harness, compacted in harness, and discharged. Before mixing water is heated up to 25-100°C and caustic sodium (NaOH) or potassium (KOH) soda as processing additive is introduced. Dicalcium silicate in form of self-moldering slag is used as cement.

EFFECT: decreased cost, increased content of available components, shorter briquette conditioning time, briquettes of increased strength more dense structure.

2 ex, 2 tbl

Description

The method relates to metallurgical, foundry, construction industries, to methods of briquetting powdered materials, mainly from waste from metallurgical production.

Widely known methods for the manufacture of briquettes from powdered ore materials and waste from metallurgical production using various types of building cements as binders (Ravich B.M. Briquetting in non-ferrous and ferrous metallurgy. - M .: Metallurgy, 1975. - P. 44- 45; Lurie L.A. Briquetting in Metallurgy.- M .: Metallurgizdat, 1963. - P.141-142).

These methods for the production of briquettes include the preparation of a mixture by mixing powdered fillers in the form of ore materials or metallurgical waste, a binder in the form of building cement and water, loading the prepared mixture into a forming tool, compressing the mixture into a briquette by pressing, holding the briquette in a forming tool to harden it to air or in a steaming chamber at high temperature, unloading briquettes from equipment.

The disadvantage of these methods is the need for long exposure of briquettes in forming equipment for their hardening (from 48 to 100 hours), the need to use a large number of forming equipment, application to achieve high strength steaming briquettes in steaming chambers at high temperature and steam pressure, the use of building cements high grades, which increases the cost of production of briquettes.

Closest to the technical nature of the claimed invention is a method for the manufacture of briquettes from powdered waste ferrosilicon (Kanaev Yu.P., Bondarev A.A. Pelletization of small waste ferrosilicon. Improving the production of ferrosilicon. Issue No. 3. Materials of the factory scientific and technical conference. - Novokuznetsk, 1997 .-- S.394-396).

The specified method involves mixing dust of FS75 grade ferrosilicon with construction grade 200 cement at a 4: 1 ratio, bringing the mixture to concrete consistency with water, loading (pouring) it into a forming tool (cassette molds with a 70 × 70 cell), drying the mixture in a snap ( forms) in the air for 48 hours, after the briquettes have reached sufficient mechanical strength, unloading the briquettes from cassette forms and additional hardening of the extracted briquettes in air.

The disadvantages of this method are:

- high consumption of branded cement (about 20%) and water (for fluidity of concrete they give about 30% water), which increase the cost of briquettes and worsen the properties of the mixture and briquettes for use in metallurgical production due to the high content of ballast: cement and water;

- low content in briquettes of the proportion of useful elements, such as silicon, due to the increased content in the mixture of cement and water;

- low activity of the useful element in briquettes, for example silicon, due to the high content of cement, which blocks a particle of the main material with a strong inactive film over a much larger area;

- long exposure of briquettes in forming equipment (from 48 hours) due to the increased humidity of the concrete mixture, which reduces the productivity of the production of briquettes, leads to high water consumption for the preparation of a fluid concrete mixture;

- insufficiently high strength of the briquettes after removal from the snap, which requires additional hardening them in the air outside the snap.

The objective of the invention is to increase the strength and reduce the cost of briquettes made from powder materials, mainly from waste from metallurgical production, reduce the consumption of cement and water, use cheap low-grade cement, increase the content of useful elements in briquettes and their activity for metallurgical processes, reduce the exposure time of briquettes in forming snap.

The problem is solved in that in the method of manufacturing briquettes from powder materials, mainly from waste from metallurgical production, including mixing the powder material with cement, technological additive and water, loading the mixture into a forming tool, compacting it in a tool, holding the compacted briquettes in a forming tool, unloading briquettes from a forming tool according to the invention, before mixing with the components, the water is preheated to a temperature of 25-100 ° C and introduced into it technological additive in the form of caustic sodium NaOH or potassium KOH soda, and dicalcium silicate in the form of self-dispersing ferrochrome slag is used as cement.

A feature of the invention is that as a binder for briquetting powdered materials, dicalcium silicate is used in the form of self-scattering ferrochrome slag in combination with a processing aid in the form of caustic sodium or potassium soda and heated water.

The dicalcium silicate proposed as a binder in self-dissolving ferrochrome slag has a crystalline structure in the form of a Y modification and contains up to 40% silica, which is chemically weakly bound to calcium oxide. Therefore, when interacting with caustic soda and heated water, silica actively passes into a colloidal ultrafine state.

This process proceeds by the following reaction:

Water heating

As a result of this reaction, colloidal sodium silicate and its hardener in the form of calcium hydroxide are released in the composition of the binder composition of the briquetted mixture, which contributes to the coagulation of colloidal sodium silicate and thereby plasticizes and strengthens the mixture.

At the same time, the hardening rate of the mixture proceeds at a high speed, which eliminates the long exposure of briquettes in the forming tooling. This process is accelerated by using heated water. The impact on the hardening rate of briquettes of potassium caustic soda is greater than that of sodium. Therefore, with their help and by changing the temperature of water heating, it is possible to adjust the hardening rate of briquettes depending on technological requirements.

Thus, low-grade cement in the form of ferrochrome slag becomes a strong hardener of mixtures based on metallurgical waste and ensures short-term residence of the mixture and compacted briquettes from it in a forming tool. When using conventional 3-calcium silicate cements in the method, this process proceeds differently due to excess CaO: a little colloidal phase is formed and a lot of hardener in the form of calcium hydroxide and curing of the mixture slows down, since the main hardener is colloidal silicate. Therefore, only dicalcium silicate provides an intensive process of hardening briquettes from powder materials using heated water and a technological additive in the form of sodium or potassium hydroxide.

Since the proposed method provides high strength properties of briquettes, the amount of binder material can be reduced and thereby increase the proportion of useful elements in briquettes from increasing the amount of briquetted material in the mixture. In comparison with the known method, the consumption of binder material is reduced by 50%.

Example 1. The manufacture of briquettes with a size of 25 × 45 × 65 mm was carried out on a roll briquette model of CJSC Ural VIM with a specific pressing pressure of 50 MPa. Preliminarily, samples were tested on mixtures depending on changes in the temperature of preheating water.

The tests were carried out in comparison with the prototype. According to the prototype, the mixture was prepared from powdered ferrosilicon grade FS65 with the addition of Portland cement grade 200 in a ratio of 4: 1 (i.e. cement content of about 20%) and the addition of water in a ratio of solid and liquid substances, like 70:30, which is usually recommended for concrete.

According to the invention, the mixture was prepared from powdered ferrosilicon grade FS65 with the addition of 10% low-grade cement in the form of self-scattering slag of ferrochrome production and 7% water heated to different temperatures with the addition of 5% NaOH.

As a control parameter, we took the strength achieved in briquettes after 5 seconds, which characterizes the achieved strength when the mixture is aged in a forming tool. For mechanized briquetting in roll briquetters, this time usually does not exceed 3-5 seconds. Therefore, the strength of briquettes after 5 seconds of exposure gives an idea of the nature of the hardening of the mixture in the forming tooling. Another indicator was the briquette strength after unloading them from the forming tooling and subsequent exposure to air for 1 hour. This parameter characterizes the further formation of briquette strength outside the forming tooling and is important in assessing the quality of briquettes.

The test results are presented in table 1

Table 1 Options Water heating temperature, ° С twenty 25 35 fifty 70 one hundred Strength after 5 s, Prototype 0 0 0.08 0.26 0.34 0.82 kPa Invention 0.8 5.2 12.6 15.4 18.8 22.7 Strength after 1 h Prototype 0.08 0.12 0.29 0.61 1.7 1.9 kPa Invention 1,1 8.2 16.7 21,4 24.5 28.9

As can be seen in table 1, to achieve the required strength of the briquettes of the prototype failed either after 5 seconds or after 1 hour of exposure. The strength of briquettes from a mixture prepared with water at a temperature of 20 ° C also does not meet the requirements, since at a strength of 0.8 kPa, the briquettes did not preserve their integrity upon exiting the forming tooling. The minimum strength of briquettes, ensuring their integrity when exiting equipment, should be at least 2.5 kPa. Therefore, the minimum temperature for heating water was 25 ° C. At the same time, the maximum temperature of water heating achieved in open containers of 100 ° C provides briquettes with high strength. This allows to reduce the content of low-grade cement in the form of self-scattering ferrochrome slag in the mixture, in comparison with the content of high-grade cement in the mixture according to the prototype, by half, i.e. up to 10 wt.%.

Example 2. Briquettes using the same technology were made from a mixture based on powdered ferrosilicon FS 65 with the addition of low-grade cement in the form of ferrochrome slag 10 wt.% And as a technological additive 3 wt.% KOH. The water content at different temperatures was introduced into the mixture in an amount of 7 wt.%.

A mixture of the prototype was prepared in the same proportions as in example 1, using Portland cement grade 200.

The test results are presented in table.2.

table 2 Options Water heating temperature, ° С twenty 25 35 fifty 70 one hundred Strength after 5 s, Prototype 0 0 0.18 0.36 0.44 0.98 kPa Invention 1,5 6.3 15.3 18.7 23.5 28,4 Strength after 1 h Prototype 0 0.18 0.32 0.53 0.98 1.43 kPa Invention 2,3 10.6 22.3 28,2 31.8 37.5

As can be seen in table 2, the mixture and method of preparation of briquettes according to the prototype do not provide the required strength for mechanized shaping with a short residence time of briquettes in the forming tooling. The method according to the invention provides the necessary strength provided that the water is preheated to a temperature of at least 25 ° C.

The test results showed that the proposed method can reduce the consumption of cement hardener in half. Moreover, low-grade cement in the form of self-scattering ferrochrome slag, which is a dump waste of ferroalloy production, can be used as cement. When implementing the proposed method, it becomes possible mechanized high-performance production of briquettes, the use of cheap grades of cement hardener and with a decrease in its consumption and water.

Industrial applicability

The method can be widely used in the processes of pelletizing, granulating and briquetting powdered materials in metallurgical and ferroalloy production in the preparation of starting materials in the processes of sintering, ore dressing, sales of waste from own and other industries.

For briquetting of powdered ferroalloy production wastes according to the proposed method, it is most advisable to use continuous blade mixers of the Pavlograd or Tyumen foundries and construction equipment, and briquetters from CJSC Ural VIM or Spidermash as briquetting equipment.

Claims (1)

A method of manufacturing briquettes from powder materials, mainly from metallurgical waste, comprising mixing the powder material with cement, technological additive and water, loading the mixture into the forming tool, compacting it in the tool, holding the compacted briquettes in the forming tool, unloading the briquettes from the forming tool, the fact that before mixing with the components of the mixture is preheated to a temperature of 25-100 ° C and introduced into it technological add herein by NaOH as caustic sodium or potassium soda KOH, and as the cement is used in the form of dicalcium silicate samorassypayuschegosya ferrochrome slag.